In the second part, we first introduce the basic theory of NMR chemical shift and the problem appeared in the calculation on the I3C NMR chemical shift tensors of the carboxyl carbon in crystal amino acids.

• 第二部分则首先介绍了基本的化学位移理论以及理论上计算晶态氨基酸分子羰基碳原子~(13)C NMR化学位移张量所出现的问题。